WEEK 2: Drugs and the large bowel Flashcards
What is diarrhea?
What are some causes of diarrhea?
State the 2 major factors in diarrhea.
Diarrhea is the passage of frequent, liquid stools. (? At least 3 times daily)
There are numerous causes of diarrhea (Infections, Toxins, Drugs, Underlying diseases, Anxiety etc.)
Increased motility of the GI tract and decreased absorption are major factors in diarrhea.
State the 3 main Treatment approaches to diarrhea.
Maintenance of fluid and electrolyte balance
Use of antimicrobial drugs
Use of antidiarrheal drugs
Many patients with diarrhea require no other treatment but rehydration.
Discuss the MOA of ORS.
Oral rehydration solution is a cheap and simple remedy. Lifesaving especially in pediatric patients.
Sodium-dependent glucose cotransport (The presence of sodium enhances absorption of sodium and water)
ORS is a preparation of glucose, sodium chloride and other salts.
State the 3 classes of anti-diarrheal drugs.
Antimotility agents
Adsorbents
Drugs that modify fluid and electrolyte transport
Discuss anti-motility agents.
MOA
Examples
Opioid agonists
Codeine. Loperamide. Diphenoxylate.
Mainly act on the μ-opioid receptors in the myenteric plexus, which increases the tone and rhythmic contraction of the intestine but lessens propulsive activity
Q: What is the mechanism of action of racecadotril?
Q: How does racecadotril work?
Q: What conditions is racecadotril used to treat?
A: Racecadotril is an oral enkephalinase inhibitor.
A: Racecadotril works by inhibiting the activity of enkephalinase, an enzyme responsible for breaking down enkephalins in the intestine.
By inhibiting enkephalinase, racecadotril increases the levels of enkephalins, which are natural opioids that regulate fluid secretion in the intestine.
This results in reduced fluid secretion and thus helps alleviate diarrhea symptoms.
A: Racecadotril is primarily used to treat acute diarrhea, including both infectious and non-infectious diarrhea in adults and children.
Q: What are the therapeutic uses of codeine?
Q: How does codeine exert its effects in the body?
Q: What are some examples of drugs that inhibit the activity of CYP2D6?
A: Codeine is primarily used as an analgesic (pain reliever) and antitussive (cough suppressant).
A: Codeine is metabolized by the liver enzyme CYP2D6 into morphine, which is responsible for its analgesic properties. Morphine binds to opioid receptors in the brain and spinal cord, reducing the perception of pain and suppressing cough reflexes.
A: Examples of CYP2D6 inhibitors include bupropion, fluoxetine, paroxetine, quinidine, and terbinafine.
These drugs can interfere with the metabolism of codeine, potentially altering its effectiveness or increasing the risk of adverse effects.
Q: Does codeine cross the blood-brain barrier?
Q: What are some risks associated with the use of codeine?
Q: How is codeine typically classified in terms of its potential for addiction and abuse?
A: Yes, codeine is able to cross the blood-brain barrier, allowing it to exert its effects on the central nervous system.
A: Codeine carries the risk of respiratory depression, particularly in higher doses or when combined with other respiratory depressants such as alcohol or benzodiazepines.
Additionally, codeine has the potential for addiction and abuse, leading to its classification as a Schedule III controlled substance in many countries.
A: Codeine is classified as a Schedule III controlled substance due to its potential for abuse and dependence.
This classification reflects its moderate to low potential for physical and psychological dependence compared to Schedule II opioids like morphine or oxycodone.
However, misuse of codeine can still lead to addiction and other adverse consequences, emphasizing the importance of cautious prescribing and monitoring.
Q: What type of drug is loperamide and what is its availability?
Q: What is the relationship between loperamide and meperidine?
Q: How is loperamide absorbed in the body?
A: Loperamide is a non-prescription drug, meaning it is available over the counter without a prescription.
A: Loperamide is a meperidine congener, meaning it shares some structural similarities with meperidine, a synthetic opioid analgesic.
A: Loperamide is poorly absorbed from the gut, which is why it is commonly used to treat diarrhea as it acts locally in the intestines.
Q: Does loperamide have the ability to affect the central nervous system?
Q: What are the typical uses of loperamide?
A: Loperamide barely crosses the blood-brain barrier, meaning it has limited ability to affect the central nervous system. This property helps to reduce the potential for central nervous system side effects commonly associated with opioid medications.
A: Loperamide is primarily used to treat acute and chronic diarrhea.
It works locally in the intestines by slowing down bowel movements and reducing the frequency of diarrhea without causing significant central nervous system effects.
However, it is important to use loperamide as directed and not exceed the recommended dose, as misuse can lead to adverse effects and potential complications.
Q: What type of drug is diphenoxylate and what is its relationship to meperidine?
Q: What are some effects of diphenoxylate on the central nervous system?
Q: How is overuse of diphenoxylate discouraged in commercial preparations?
A: Diphenoxylate is a medication related to meperidine, belonging to the same class of synthetic opioid analgesics.
A: Diphenoxylate has the potential to penetrate the central nervous system (CNS) at high doses. This can lead to a sense of false euphoria and is associated with the potential for habit-forming or addictive behaviors.
A: Commercial preparations of diphenoxylate, such as Lomotil, contain atropine alongside diphenoxylate. Atropine is included to discourage overuse by causing unpleasant side effects if taken in excessive amounts.
Q: What is Lomotil and what does it contain?
Q: What should individuals be aware of when using diphenoxylate?
A: Lomotil is a medication used to treat diarrhea, and it contains a combination of diphenoxylate and atropine.
Diphenoxylate helps to reduce bowel movements and relieve diarrhea symptoms, while atropine helps to discourage overuse and counteract potential side effects of diphenoxylate.
A: Diphenoxylate has the potential for central nervous system effects, including a sense of euphoria, and is associated with the risk of habit-forming behaviors.
It is important to use diphenoxylate as directed by a healthcare provider and to avoid exceeding the recommended dose to minimize the risk of adverse effects and addiction.
Q: What are some common uses of antimotility drugs?
Antimotility drugs are often used for non-infective, idiopathic, exhausting diarrhea as a short-term measure only.
Also used post-anal surgery and in ileostomy/colostomy patients
Contraindication of antimotility drugs
Q: Why are antimotility drugs contraindicated in infective diarrheas?
Q: Why should antimotility drugs be avoided in diverticulosis and ulcerative colitis?
Q: Why is the use of antimotility drugs cautioned in children?
A: In infective diarrheas, it’s important for the body to expel the infectious agent causing the diarrhea.
Antimotility drugs, by slowing down bowel movements, can inhibit the body’s natural defense mechanism of clearing the infection through bowel movements, potentially prolonging the illness.
A: Antimotility drugs may increase the risk of complications such as bowel obstruction or perforation in patients with diverticulosis.
In ulcerative colitis, slowing down bowel movements may exacerbate inflammation and worsen symptoms.
A: The use of antimotility drugs in children is generally avoided due to the risk of serious adverse effects, including toxic megacolon, a potentially life-threatening condition characterized by severe dilation of the colon.
Children are more susceptible to adverse effects of these medications, so alternative treatments are often preferred.
Q: What are two examples of adsorbents used in managing diarrhea?
Q: What are some possible mechanisms of action of adsorbents?
A: Two examples of adsorbents used in managing diarrhea are methylcellulose and aluminum hydroxide.
A: Adsorbents such as methylcellulose and aluminum hydroxide may work through several mechanisms, including:
*Adsorption of intestinal microorganisms and toxins: Adsorbents bind to microorganisms or toxins in the gastrointestinal tract, preventing them from causing irritation or further inflammation.
*Coating and protecting intestinal mucosa: Adsorbents form a protective layer over the intestinal lining, helping to soothe and shield the mucosa from further damage.
Q: How do adsorbents compare in effectiveness to antimotility drugs in managing diarrhea?
Q: What is a potential drawback of using adsorbents?
A: Adsorbents are generally considered to be less effective than antimotility drugs in managing diarrhea.
While they can provide relief by adsorbing toxins and protecting the intestinal mucosa, antimotility drugs directly slow down bowel motility, which can be more effective at reducing stool frequency and urgency.
A: One potential drawback of using adsorbents is that they may decrease the absorption of other drugs taken concurrently.
This can reduce the effectiveness of medications that rely on gastrointestinal absorption for their therapeutic effects.
Therefore, it is important to take adsorbents and other medications at separate times to minimize this interaction.
Q: What is the primary use of aluminum hydroxide?
Q: What effect does aluminum hydroxide have on bowel movements?
Q: What is a notable characteristic of aluminum hydroxide in terms of phosphate binding?
A: Aluminum hydroxide is primarily used as an antacid to relieve symptoms of heartburn, acid indigestion, and upset stomach.
A: Aluminum hydroxide has constipating effects, meaning it can slow down bowel movements and reduce stool frequency. This property makes it beneficial for individuals who experience diarrhea or loose stools.
A: Aluminum hydroxide has an excellent phosphate binding capacity, which means it can effectively bind to phosphate in the gastrointestinal tract.
This property makes it useful in the management of conditions associated with elevated phosphate levels, such as hyperphosphatemia.
Q: What potential adverse effect is associated with aluminum hydroxide’s phosphate binding capacity?
Q: How does aluminum hydroxide compare to magnesium hydroxide in terms of its effect on bowel movements?
A: The strong phosphate binding capacity of aluminum hydroxide can lead to hypophosphatemia, a condition characterized by low levels of phosphate in the blood.
This can occur when aluminum hydroxide binds to phosphate in the gastrointestinal tract, preventing its absorption into the bloodstream.
A: Unlike magnesium hydroxide, which acts as a laxative and can promote bowel movements, aluminum hydroxide has constipating effects and tends to slow down bowel movements.
Magnesium hydroxide is often used to relieve constipation, while aluminum hydroxide is more commonly used to alleviate diarrhea or acid-related stomach discomfort.
